package com.tx.weixin.util;

import java.security.MessageDigest;
import java.util.Arrays;

public class CheckUtil {
    public static final String token = "jst9528";

    public static boolean checkSignature(String signature,
                                         String timestamp,
                                         String nonce) {
        //1.定义一个数组存放token,timestamp,nonce
        String[] arr = {token, timestamp, nonce};
        //2.对数组排序
        Arrays.sort(arr);
        //3.生成字符串
        StringBuffer sb = new StringBuffer();
        for (String s : arr) {
            sb.append(s);
        }
        //4.sha1加密
        String temp = getSha1(sb.toString());
        //5.将加密后的字符串，与微信传来的加密签名比较返回结果
        return temp.equals(signature);
    }

    //加密梳理
    public static String getSha1(String str) {
        if (str == null || str.length() == 0) {
            return null;
        }
        char hexDigits[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
        try {
            MessageDigest mdTemp = MessageDigest.getInstance("SHA1");
            mdTemp.update(str.getBytes("UTF-8"));
            byte[] md = mdTemp.digest();
            int j = md.length;
            char buf[] = new char[j * 2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte b = md[i];
                buf[k++] = hexDigits[b >>> 4 & 0xf];
                buf[k++] = hexDigits[b & 0xf];
            }
            return new String(buf);
        }catch (Exception e){
            return null;
        }
    }
}
